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CHAPTER VI 

 FOOD FISHES 



1 THE shipmen sounded, and found it twenty fathoms.' 

 Acts xxvii. 27-8. As you stand on the sea- shore and watch 

 the tide come in, you notice that gradually a strip of sand or 

 pebbles, where an hour or so ago you could walk in perfect 

 safety, becomes covered with water until at last all the beach 

 is hidden, and you say the tide is in. Yet, though you cannot 

 see it, you know that under the water the beach is there, 

 and if you were in a boat you could let down a line weighted 

 with a piece of lead and measure how deep the water was at 

 any particular spot. 



Just in the same way beyond low- water mark there is 

 a sea-floor, and, though the water never recedes and makes 

 it visible, we can measure its depth in the same way as we did 

 that of the beach. Of course, the farther away from the land 

 you go the deeper becomes the sea, and the longer the line 

 you will have to let out, yet you will find that the depths 

 vary, and that, just as we have hills and plains on shore, so 

 at the bottom of the sea there are heights and hollows, places 

 where the sea is shallow and where it is deep. 



For many years men have patiently ' taken soundings ', 

 as it is called, of the seas of the world, until now they can map 

 out the floor of the sea almost as accurately as the surface 

 of the land. Looking at such a map we notice that round 

 the British Isles the sea is nowhere deeper than 100 fathoms, 

 i. e. 600 feet. Beyond this shallow area the water gets deeper 

 and deeper until far out in the ocean depths of 3,000 and 

 4,000 fathoms have been sounded and even in some places 

 more than 5,000. 



The edge of this 100-fathom area is called the 100-fathom 

 line. It runs close into the coasts of Spain and Portugal, 

 branches towards the north-west in the Bay of Biscay, and 

 then runs round the west of Ireland and north of Scotland. 



